Plastics and the ocean: Origin, characterization, fate, and impacts. A.L. Andrady (ed.) 2022. John Wiley & Sons, 484 pp. ISBN 9781119768401 (Hardcover: £148)
Plastics are on everyone's lips, both figuratively and, unfortunately, literally. And the latter case, when we humans ourselves face a threat, is always the decisive wake-up call in recognizing and acting upon a particular pollution problem. This is a long review, probably the longest I have written in my tenure as book review editor, and also largely a rather unusual “chapter-by-chapter” format, but this simply reflects the enormous scope and depth of the issues addressed by 41 contributing authors in 16 chapters, who tackle virtually every aspect of plastics as a threat to the world's oceans (and to our health).
Even the Preface is a concentrated gem including a wonderful historical account highlighting key players on this topic and the early push-back from industry. It notes the Life magazine issue announcing the dawn of the plastic era with “throw-away living”. And, indeed, this moniker – today expressed by the more modern term “single-use” – proves to be the crux of the entire conundrum. The landslide of plastic ultimately prompted an explosion of papers in scientific journals, a series of international marine debris conferences, the emergence of environmental protection organizations around the globe targeting the issue, annual beach clean-ups, legislation on all levels and a long list of reports and books, including this most recent one.
Chapter 1, Plastics and the Anthropocene, sets the framework by very thoroughly answering the question “what are plastics”. This chapter is a true “everything you always wanted to know about plastics” – their composition, types and uses, behaviours, the amounts produced, production trends, relative degradability, social costs and benefits (yes, there are many benefits too). It also includes a first foray into plastics/microplastics (along with definitions) in the ocean, even an extra “box” on the much-discussed paper-versus-plastic-bag “proxy war”. Digesting this chapter alone will make you all the expert you need to be if you are interested in the field of marine debris/beach litter. Interestingly, the prognosis for the availability of the basic ingredient in plastics, namely fossil fuels, is better than ever considering that major reserves will be freed up by the expected growth of electric vehicles. The take-home message is that plastic production – and therefore the amount entering the ocean – will continue to increase in the coming decades, and that the only factor that can dampen the onslaught is a deliberate reconsideration of the products we use and the way in which they are ultimately disposed of. Is the search for the faulty party the classic “It's you and me, baby”? Yes and no. This aspect is reminiscent of so many things in modern life, where the powers to be like to shift the blame and burden onto consumers, whether this be buried in the fine print of insurance policies, in excessive instruction manuals with lengthy warning and safety preambles serving as disclaimers, or making you personally responsible for virtually each and every banking procedure – the consumer is left holding the bag, which is perhaps a truly apt metaphor for the issue at hand. Thankfully, transitions are in the making, and not all of them rest on the shoulders of consumers. Laws and conventions are being passed to reduce single-use plastics, for example. And, importantly, those efforts were largely fuelled by citizen pressure, in no small part because of plastics in the ocean, so you and I have more power than we might think.
Chapter 1 goes on to summarize eight categories of environmental threats by plastics in the ocean. Only one of them is the aesthetic damage that most people first associate with this form of pollution. The list of papers cited in the Reference section of this chapter alone exceeds 200, a laudable marquee of all the chapters of this book. In fact, the wealth of references here is yet another celebration of the book form over that of the scientific journal format. Where else can you get such a compilation and synthesis of detailed insights in one work? Conversely, where else could you as an author supply hundreds of references for each of the treated subjects? Long live books!
The subsequent chapters then go into great detail on the topics introduced in Chapter 1. Chapter 2, for example, treats the chemical components (additives) meant to improve the properties of plastics (introduced as an issue on p. 20 of the first chapter). Beyond the main ingredient of plastics, namely, polymers, somewhere between 1% and 50% by weight can be made up of plasticizers, fillers, flame retardants, antioxidants, heat stabilizers, impact modifiers, lubricants, light stabilizers, colorants and reinforcements. And we are talking about 2000 million metric tons of such additives being produced by 2050, with an estimated 200 tons entering the oceans in 2015 alone, an amount expected to double by 2025. The end result: these compounds make plastics more durable, which might be positive for consumers but is negative once the items enter the sea. The authors list somewhere around 175 references to back up their information on the sources, releases, transport, degradation, detection and toxicity of such additives.
Chapter 3 reviews three basic scientific methodological approaches to plastic pollution: emission rates, transport models and pollution identification. The latter is nicely illustrated (Fig. 3.3) based on the useful features of a discarded plastic bottle. Overall, the approaches address sources, pathways and sinks. The conclusion: only integrating the methods can help solve the problem, and three strategies are presented to improve such collaboration.
Chapter 4 gets into the nitty-gritty by outlining how to collect and characterize microplastic debris from water, sediments, macrophytes, plankton, shellfish and fish. Beyond visual microscope observation, the array of instruments required to chemically characterize the items is daunting and points to the necessity for high-tech labs. Each method has its advantages and disadvantages, admirably compiled in Table 4.4. Even all these approaches can fail to do the trick, with the authors therefore calling for improving existing analytical methods and developing novel ones.
Chapter 5 goes into detail on estimating microplastics in deep water. It might sound relatively easy, but what about the confounding roles of biofilms, faecal pellets or macro-aggregates (“marine snow”). Thousands of polymers have been produced, and “each such microplastic should be thought of as being dynamic rather than having fixed parameters” regarding intrinsic properties while floating and sinking in the water column. The many current deficiencies in our knowledge here (as reported in virtually every chapter of this book) make this sound like yet another daunting task.
Where does all the plastic in the oceans end up and why is only a small part found in surface waters? The answer is the sea floor (Chapter 6). In this respect, half the plastics produced are heavier than seawater. If plastics degrade due to wear and tear, heat and sunlight, then these processes all come to a halt in the cold, dark, calm deep sea, meaning long-term accumulation and storage there. As expected, documenting and retrieving plastic/microplastic samples from deeper sea floors is yet another true challenge. The items range in size from microplastics (MPs) to mega-litter (the latter often fisheries-related items: the term ALDFG – abandoned, lost or discarded fishing gear – is introduced here but not included in the Index). Two multi-page tables summarize the information on sea-floor litter collected by trawling and imagery respectively. Overall, this book admirably did not shy away from providing colour images, and the 8-photo plate of sea-floor litter in this chapter (Fig. 6.3) is a case in point. I do note that, in this plate, the depicted barrel is not plastic, and I had to look up the genus Leiopathes (a branched hexacoral), which is difficult to spot and may be less “entangled” by fishing gear than actively growing on them, pointing to potential benefits of sunken marine debris as a rare substrate for sessile species, as the authors duly note under “Impacts” on p. 178.
Overall, many gaps in our knowledge are identified in this book (e.g. dozens on p. 184/185). There is much to do, but, importantly, this recognition cannot be an excuse to wait until the full information is available and confirmed before taking remedial action. The nearly 200! references in Chapter 6 signify that we know enough to take action today.
Although the book is titled “Plastics and the Ocean”, Chapter 7 deals with this material in freshwater bodies. Beyond their well-known role in transporting plastics and other debris into the sea, freshwater bodies and their different compartments and food webs can themselves be polluted. This is exemplified in one of the cited papers that sticks to my mind – probably because it struck “close to home” – that found more plastic litter than fish larvae during a Danube River sampling effort (for larvae). The culprit: a major company that had for years been “losing” vast amounts of plastic pellets in its manufacturing process.
The great many degradation and fragmentation processes are outlined in detail in Chapter 8. The photo of the macro-fragmentation in Fig. 8.10 is, however, clearly of a bottle rather than a cup as stated. While plastic does not really “disappear”, at least this reviewer hopes that some of the traditional charts specifying the long times plastic items remain in the ocean environment are somewhat misleading (e.g. will a plastic bottle really last several hundred years if it is exposed to sunlight, abrasion, etc.?).
Of course, plastics not only release pollutants (e.g. additives), they also sorb and concentrate them (Chapter 9). These can then be released into different aquatic environments and to organisms. This includes antibiotics and an array of persistent organic pollutants (POPs) and highlights yet another aspect of the threat that plastic pollution poses.
Chapter 10 “Colonization of Plastic Marine Debris” is perhaps a slight misnomer because rather than treating the rafting of encrusting organisms to the far ends of the globe as might be expected, it is restricted to microbial life (“rafting” is not in the Index either, but “biofouling” is). Importantly, however, every initial colonization will be microbial, and the term “Plastisphere” is introduced to describe that thin layer of life (“biofilm”) that colonizes the outer surfaces of plastic debris. And this more often than not initially involves diatoms rather than bacteria. What does it all mean? Although much is known, even more seems unknown or unknowable (as per the chapter's subtitle).
Chapter 11 treats the biodegradation of plastics, as opposed to the chemical degradation processes outlined in Chapter 8. This is defined as degradation caused by the action of living organisms, whereby the authors distinguish an extracellular enzymatic breakdown (“biotransformation”) versus assimilation of the resulting products (“biomineralization”). The authors also take a jab at the claims surrounding “biodegradable” plastic items and, overall, do not consider biodegradation to play a significant role in most plastic debris.
This book does not focus on certain conspicuous facets of larger plastic items in the sea such as entanglement, rafting or ingestion (but see Table 12.1). It does concentrate on microplastics, and Chapter 12 is a case in point. Ingestion of MPs has become a hot topic in the scientific literature (Fig. 12.1) and this is especially conspicuous in this chapter: 10 pages of text, 8 pages of references! Microplastics are in the same size range as the prey ingested by many marine organisms (think of all filter-feeders). Microplastics – and their contaminants – are known to cause damage at all levels of organization, but, as concluded in many other chapters, the underlying ecotoxicological effects and mechanisms are still poorly understood. As in all forms of pollution, things get serious and trigger critical attention once they start to appear in seafood (Chapter 13). The risk is clearly there but, again, quantifying and relativizing it – for example, in comparison with the microplastics released from tea bags, baby bottles, etc. – represents a challenge requiring a wealth of data on the full range of consumed marine species and their feeding behaviours as well as detailed human dietary patterns (multi-page Table 13.1). Not to mention data on specific chronic health effects. The trick is to avoid being counterproductive considering the known health benefits of consuming seafood.
What happens to the untold number of microplastic items? One answer is that each and every one of them will become even smaller, leading to the issue of nanoplastics (Chapter 14, subtitled “The unseen majority”). If microplastics can shunt themselves up through the food chain, won't that be even truer of nanoplastics? The first semi-quantitative proof of nanoplastics in the environment stems only from 2017. Nonetheless, 10 pages of references (only very few before 2015) point to hectic work here. This means that this issue is in its infancy, and there is not even a consensus on the definition of this size class (although, as in microplastics, there is a distinction between primary and secondary nanoplastics). The methodological challenges (Table 14.2) in making progress here seem to exceed even the considerable ones in microplastics. The hypothesis, however, is that this category may account for the largest percentage of unaccounted plastic in marine debris. Nanoplastics are capable of acting at the cellular level, resulting in a new dimension of toxicological concerns. Again, impacts on humans are a driving force behind the as yet mostly experimental, laboratory-based research (restricted to primary nanoplastics), and a table of toxicological effects on various marine organisms relevant to the seafood industry is presented (Table 14.1).
This book ends with one chapter (15) on human behaviour and one (16) on legal frameworks related to marine plastic pollution. This highlights the fact that we humans are responsible for this plight and at the same time are the “most valuable resource” in the fight against it. What are the attitudes worldwide regarding recycling? Can the attitudes of adults be changed/reversed? Or do we have to rely on better education for the younger generation? Buy this book and find out the answers.
It is in some way heartening that legal frameworks are rapidly being put in place. These are a mix of binding and voluntary instruments rather than a single, binding international agreement on the full life cycle of plastics including marine litter. Nonetheless, this means that all those fighting the good fight can call up a wide range of international, regional and local legal frameworks, and not rely solely on “bleeding heart” arguments.
We have all heard of hotspots such as the Giant Pacific Garbage Patch and perhaps of the other gyres associated with similar marine litter concentrations, but how does the average citizen encounter plastics in the ocean? Correct – on their vacation beach. On some, beach-goers are more likely to encounter plastic debris than the traditional snail and clam shells, algae and other natural beach wrack tossed up by the waves. Importantly, marine debris involves much more than plastic, but includes glass, metal, clothing, treated wood, paper, smoking paraphernalia, medical wastes, etc. As an outgoing book review editor – and to underscore my partiality on the issue – I am taking the liberty of shamelessly citing my own book “The Beachcomber's Guide to Marine Debris”. In light of the citizen science movement, all the relevant brochures, reports, books and TV programs are a call for everyone to get involved. Become a beach detective, take one more piece of plastic home than you brought to the beach, join a clean-up, shame egregious polluters and write to your legislators. After all, plastic and other marine debris are just about the only form of marine pollution that you and I can do something about personally, both with respect to prevention and removal. See you on the beach!
